Filter products are mainly categorized by spectral band, spectral characteristics, film material, application characteristics and other ways.
Spectral bands: ultraviolet filters, visible filters, infrared filters;
Spectral characteristics: bandpass filters, cut-off filters, spectral filters, neutral density filters, reflective filters;
Membrane materials: soft filters, hard filters;
Hard filters are not only in terms of film hardness, but also in terms of laser damage threshold. It is widely used in laser systems because of its damage threshold, while soft film filters are mainly used in biochemical analyzers.
Band-pass type: The light of the selected band passes through, and the light outside the passband is cut off. Its optical indicators are mainly the center wavelength (CWL), half-bandwidth (FWHM). Divided into narrowband and broadband. For example, narrow-band 808 filter NBF-808.
Short wavelength pass type (also called low wavelength pass): shorter than the selected wavelength of light through the light longer than the wavelength cutoff. For example, infrared cutoff filter, IBG-650.
Long wavelength pass type (also called high wavelength pass): light longer than the selected wavelength passes through, shorter than the cutoff of the light at that wavelength. For example, infrared transmittance filter, IPG-800.